portable

## Rules for Manual Scans

This topic discusses rules for manual scanning using a hard probe on a portable device.

Rules for Manual Scans in General

The following description lists the rules that you must follow to have manual scanning compensate correctly and with greater speed on Arm devices.

- You should not lock any axis during the scan. PC-DMIS takes the scan by crossing the probe over a keyed-in Body Axis location. Each time the probe crosses this given plane, the Arm device takes a reading and passes it to PC-DMIS.

- On this type of scan, you must type the InitVec and DirVec values in the Part Coordinate System. This is required to work together with the Body Axis location.

- Make sure you type the Body Axis in the Part Coordinate System.

When multiple rows of manual scans are being done, we recommend that every other scan line be reversed.

For example (continuing the scan of the sphere as outlined above):

1. Begin the scan along the surface in the +X direction.

2. Move to the next row and scan along the -X axis.

3. Continue to switch the direction of the scan as needed. The internal algorithms depend on this kind of regularity and could give poor results if the scheme is not followed.

Compensation Limitations

With Fixed Distance, Fixed Time / Distance, and Fixed Time scan, PC-DMIS automatically lets you take manual hits in a three-dimensional manner and in any direction. This is useful when scanning using free moving a manual device (such as a Romer or Faro arm) whose axes cannot be locked.

Since you can move the probe in any direction, PC-DMIS cannot accurately determine the proper probe compensation (or the Input and Direction vectors) from the measured data.

There are two solutions to the compensation limitations:

- If CAD surfaces exist, then you can select FINDNOMS from the Nominals list. PC-DMIS attempts to find the nominal values for each measured point in the scan. If the nominal data is found, then the point is compensated along the found vector, which allows proper probe compensation; otherwise, it remains at Ball Center.

- If CAD surfaces do not exist, then probe compensation does not occur. All data remains at Ball Center with no probe compensation occurring.